The body of a motor vehicle with a spring suspension system tends to roll toward the outside during a turn. The roll lifts the side of the vehicle on the inside of a turn and lowers the side of the vehicle on the outside of a turn. This results in shifting the vehicle center of gravity toward the outside of a turn and shifting weight from the vehicle wheels on the inside of a turn. The body roll can also raise the center of gravity. As vehicle speed increases, centrifugal force effectively acting on the center of gravity of the vehicle will shift even more weight from the tires and wheels on the side of the vehicle on the inside of a turn to the tires and wheels on the side of the vehicle on the outside of a turn. If too much weight is removed from the tires and wheels on the side of a vehicle that is on the inside of a turn, the driven tire and wheel on that side of the vehicle will loose traction and spin. In the event that even more weight is transferred from the tires and wheels on the side of the vehicle that is on the inside of a turn, these tires can leave a road surface and the vehicle can roll over on its top.
High performance vehicles, such as racing vehicles, are designed with a low center of gravity. The low center of gravity substantially reduces weight transfer from the tires on one side to the tires on the other side. A stiff suspension system and stabilizer bars reduce body roll and further reduce the tendency of a vehicle to roll over.
A low center of gravity and a stiff suspension system will substantially reduce the tendency of a vehicle to roll over in a turn. When a high performance vehicle attempts to negotiate a turn at a speed which is too high, a driven wheel on the side of the vehicle on the inside of a turn starts to spin as the tire's ability to transfer torque from the engine to the road surface decreases. The coefficient of friction between a vehicle tire and a road surface when a tire is in sliding contact is substantially less than it is when a tire is in rolling contact with a surface. As a result, once the driven tire starts to spin, the frictional force exerted on the tires by the road is insufficient to keep the driven tires on both sides of a vehicle from sliding sideways. When the tires start to slide sideways, the vehicle will spin unless the driver can react quickly to stabilize the vehicle.
Efforts are constantly under way to improve the stability of race cars. If stability can be improved, speed can be increased, and races can be won. Increasing stability in passenger vehicles can reduce roll-overs and spin-outs.